In-ear monitors, or simply IEMs or in-ears, are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a personal mix of vocals and stage instrumentation for live performance or recording studio mixing. They are also used by television presenters to receive vocal instructions, information and breaking news announcements from a producer that only the presenter hears. They are often custom-fitted to an individual's ears to provide comfort and a high level of noise reduction from ambient surroundings. Their origins as a tool in live music performance can be traced back to the mid-1980s.A stage monitor system is any system that provides a mix of audio sources to a performer on stage. Traditionally, loudspeakers were placed on the stage directed toward the performers. These loudspeakers can have disadvantages. First, floor wedges greatly increase the onstage volume, in some cases to potential hearing damage levels. Second, while floor wedges can be placed in front of a particular singer, guitarist, bassist, or drummer, the other musicians can often hear the other musicians' wedge mixes. In a sophisticated monitoring system, every band member can have their own monitor mix, which is their particular preference of vocals or instruments.
